AP Biology

Element

A substance that cannot be broken down into simpler substances by chemical means.

Trace Element

Elements required by an organism only in very small quantities, such as iron (Fe), iodine (I), and copper (Cu).

Isotope

Atoms that have the same number of protons but differ in the number of neutrons.

Ionic Bond

A type of bond formed when one or more electrons are transferred from one atom to another.

Covalent Bond

A bond formed when electrons are shared between atoms.

Hydrogen Bond

Weak chemical bonds that form when a hydrogen atom covalently bonded to an electronegative atom is attracted to another electronegative atom.

Capillary Action

The ability of water to rise up the roots, trunks, and branches of trees due to cohesion and adhesion.

Acidic Solution

A solution that contains a lot of hydrogen ions (H+).

Base

A substance that releases hydroxide ions (OH–) when added to water.

pH Scale

A scale numbered from 1 to 14 that indicates whether a solution is acidic, basic, or neutral.

Organic Molecule

Molecules that contain carbon.

Polymer

A chain of repeating units called monomers.

Hydrolysis

The process that breaks polymers down into monomers using water.

Monosaccharide

The simplest form of carbohydrates, which are energy sources for cells.

Glycosidic Linkage

The bond formed between two monosaccharides when they join together.

Polysaccharide

A carbohydrate that consists of many monosaccharides.

Amino Acid

Building blocks of proteins that contain carbon, hydrogen, oxygen, and nitrogen.

Dipeptide

A molecule formed from two amino acids bonded together.

Peptide Bond

The bond that links amino acids together to form a peptide.

Protein

A macromolecule important for structure, function, and regulation of tissues and organs.

Lipid

Molecules made primarily of carbon and hydrogen; they include triglycerides, phospholipids, and steroids.

Phospholipid

A lipid containing two fatty acids and a phosphate group, essential for cell membranes.

Nucleic Acid

Molecules made up of nucleotides; DNA and RNA are examples.

Cell Cycle

The life cycle of a cell, including the stages of interphase and mitosis.

Homeostasis

The conditions under which living things can successfully survive.

Mitosis

The process of cell division that results in two identical daughter cells.

Cancer

A condition arising when normal cells grow and behave abnormally.

Signal Transduction

The process by which an external signal is transmitted to the inside of a cell.

Cohesive Forces

The tendency of water molecules to stick together.

Facilitated Transport

The process of transporting substances across a membrane with the help of carrier proteins.

Active Transport

Movement of substances against their concentration gradient, requiring energy.

Feedback Inhibition

A negative feedback pathway that inhibits the process of a metabolic pathway.

Glycolysis

The first stage of cellular respiration, breaking glucose down into pyruvic acid.

Krebs Cycle

The stage of cellular respiration that generates energy through the oxidation of acetyl-CoA.

Oxidative Phosphorylation

The last stage of cellular respiration where ATP is produced using the electron transport chain.

Fermentation

An anaerobic process that allows glycolysis to continue, resulting in lactic acid or ethanol production.

Photosynthesis

The process by which light energy is converted to chemical energy in plants.